Taking ACF integration to the next level

Silanna Semiconductor has expanded its CO2 Smart Power Family of AC/DC and DC-DC converter technologies with the release of an ACF controller that integrates adaptive digital PWM control with UHV components comprising a 700V primary GaN FET, X capacitor (X-Cap) discharge circuit, active clamp driver and start-up regulator.

The company's CO2 Smart Power technologies assist engineers by simplifying design and improving performance while managing environmental sustainability goals through more efficient energy use. Ideal for high-efficiency and high-power-density power supplies, USB-PD/QC AC/DC power adapters and battery charging applications, the new SZ1200 integrated ACF controller combines the ease of design of a simple flyback controller with all the benefits of ACF. These include recycling the flyback transformer's leakage inductance energy and limiting primary FET drain voltage spikes during turn-off events.

Delivering above 93% efficiency at low line, the device provides consistent efficiency across the universal input voltage range (90-265VAC) and various loading conditions of up to 150W single-port and multi-port USB-PD applications. The company's OptiMode digital control architecture adjusts operation mode on a cycle-by-cycle basis to maintain high efficiency, low EMI, fast dynamic load regulation and other key power supply parameters as line voltage and load vary. Low no-load power consumption for the most stringent USB-PD applications minimises energy use during system stand-by.

"Our goal is to make it as easy as possible for power design engineers to develop ultra-efficiency, high-density power conversion designs in the shortest time possible," says Ahsan Zaman, Silanna Semiconductor's director of Product Marketing. "The addition of the SZ1200 to our family of ACF technologies supports this goal by offering high-speed switching, unprecedented levels of integration and functionality that ensures optimum efficiency across wide input and loading conditions while minimising EMI."

By enabling designers to program switching frequency to 250kHz, the new controller supports high power densities while advanced digital active clamp operation ensures best-in-class efficiency. Switching frequency is confined within a tight frequency band to simplify EMI filtering. Further efficiency and EMI performance benefits are realised through adaptive digital control of the active clamp operation, which allows near ZVS turn-on of the primary FET and clamps the drain voltage during the turn-off.

The new device also includes CCM operation, which delivers up to 225% rated output power for a limited duration without sacrificing the power density. This feature is aimed at applications requiring peak power, such as laptop and notebook power adapters.